The present invention relates to a phenylenediamine derivative suitable for an electric charge transferring material in a photosensitive material, and also relates to a photosensitive material using such a derivative.
As a photosensitive material in an image forming apparatus such as an electrophotographic copying apparatus, there has recently and widely been used an organic photosensitive material which is excellent in machinability and advantageous in production cost and which offers a great degree of freedom for design of performance.
For forming a copied image with the use of a photosensitive material, the Carlson process is widely used. The Carlson process comprises the steps of uniformly charging a photosensitive material with electricity by corona discharge, exposing the charged photosensitive material to a document image, thereby to form an electrostatic latent image corresponding to the document image, developing the electrostatic latent image by a toner containing developer, thereby to form a toner image, transferring the toner image to paper or the like, fixing the toner image thus transferred, and cleaning the photosensitive material to remove toner remaining thereon after the toner image has been transferred. To form an image of high quality in the Carlson process, it is required that the photosensitive material is excellent in charging and photosensitive characteristics and presents a low residual potential after exposed to light.
Conventionally, there have been known inorganic photoconductive materials such as selenium, cadmium sulfide and the like as photosensitive materials. However, these inorganic photoconductive materials are toxic and need great production costs.
There has been proposed a so-called organic photosensitive material using various organic substances in place of the above-mentioned inorganic substances. Such an organic photosensitive material has a photosensitive layer comprised of an electric charge generating material for generating electric charges by light exposure and an electric charge transferring material having a function of transferring the electric charges thus generated.
To meet various requirements for the organic photosensitive material, it is necessary to properly photosensitive material, it is necessary to properly select the electric charge generating material and the electric charge transferring material. As the electric charge transferring material, there have been proposed and put on the market a variety of organic compounds such as polyvinyl carbazole, oxadiazole compounds, pyrazoline compounds, hydrazone compounds and the like. By way of example, there have been known hydrazone compounds disclosed in Japanese Unexamined Patent Publications Nos. 59143/1979 and 210451/1990.
In the electric charge transferring materials above-mentioned, however, the drift mobility representing the electric charge transferring ability is relatively small. Further, since the dependency of the drift mobility upon the electric field intensity is great, the movement of an electric charge in a low electric field is small. This makes it difficult that the residual potential disappears. Further, such materials are disadvantageously apt to be deteriorated due to irradiation of ultraviolet rays.
In view of the problems above-mentioned, there has been proposed N,N,N',N'-tetraphenyl-1,3-phenylenediamine as an example of a m-phenylenediamine derivative of which dependency of the drift mobility upon the electric field intensity is small and which has a good compatibility with respect to a resin (Japanese Unexamined Patent Publication No. 142642/1989). Such a m-phenylenediamine derivative presents good light-exposure properties with respect to ultraviolet rays and the like. When actually used in an electrophotographic copying apparatus, this derivative presents stable characteristics. However, if this derivative is exposed to light for a long period of time or at a high temperature in case of trouble of the copying apparatus, this derivative is disadvantageously damaged in an irrecoverable extent. Further, this derivative does not have sufficient sensitivity and repeat characteristics.